Hollerith Encoding

Hollerith Encoding is a system of placing information onto paper or plastic cards (punch cards) by punching holes in the card media. The system was initially used to aid the census tabulation and was based on Jacquard punch cards used to automate weaving patterns for looms.

Though it is insecure and easy to duplicate many hotels still use varients of Hollerith encoding because cheap little plastic cards are far cheaper the replace than keys.